Method for the administration of muscle relaxant drugs

ABSTRACT

769,876. Administering drugs. WELLCOME FOUNDATION, Ltd. June 20, 1955 [June 18, 1954], No. 17771/55. Class 81(2) The administration of a muscle relaxant is controlled by the response of a muscle to which an electrical stimulus is periodically applied. In the example described a device 22 supplies electrical impulses, at approximately ten-second intervals, to contact bands 20, 21, so placed as to cause contraction of the index finger towards the thumb and thereby cause closing of electrical contacts 18, 19. This energizes a relay 16 which opens an electrically operated valve 15 to allow liquid to flow from a reservoir 10 to an injection needle 11. The valve 15 comprises a solenoid operated pinch cock on a rubber tube. The tube is normally kept closed by spring pressure but energization of the solenoid overcomes this pressure and releases the tube

April 11, 1951 E. J. DE BEER Erm. 2,979,055

METHOD FOR THE ADMINISTRATION OF MUSCLE RELAXANT DRUGS Filed June 18, 1954 REMY INVENTORS [bw/Af J if 556/? BY If/.away /Z Z4/.5'

fwn-5f? /af Arm/way Unite-zi METHOD FOR THE ADMINISTRATION OF MUSCLE RELAXANT DRUG-S Edwin J. de Beer, Tuckahoe, `Charles H. Ellis, Scarsdale,

and Walter Ide, Eastchester, N.Y., assignors to Burroughs Wellcome & Co. (U.S.A.) Inc., Tuckahoe, NY., a corporation of New York Filed June 1s, 1954, ser. Nit-437,631

9 claims. (ci. 12s- 214) This invention relates to the administration of muscle relaxants for the purpose of producing a state of muscle States Patenti Vice In the drawings:

Fig. 1 shows an exemplary apparatus for measurement and supply by motor point stimulation of the index finger and electrical valve control of relaxant supply.

Fig. 2 is a detailed view of a solenoid valve controlling release of relaxant solution through the intravenous supply tube.

Fig. 3 is a kymograph recording showing muscle contraction during the administration of muscle relaxantA over a four and one-half hour period. Y

Referring to Figs. 1 and 2 of the drawings, it will be seen that a suitable device is outlinerlfor carrying out theV quired, the current to the motor muscle produces a conas such agents are needed or required to produce a denary methods of administration merely indicate a state of deep relaxation, and do not atord a wide range of safety in a patient with unassisted respiration. The present invention is based on the fact that a short lasting myoneural blocking agent which is rapidlydestroyed in the body and which has no marked cumulative action makes possible a-remarkably precise control of the degree of relaxation by regulating the amount of drug administered either by continuous infusion or by intermittent dosage. Basically, the method utilizes a means for administering a relaxant drug in combination with a means for regulating the administration of the drug by using the patients own muscles to control the dosage rate when subjected to an electrical stimulus. Muscle relaxants as used in surgery, for example, function to paralyze the nerve systems which motivate and control muscle reactions. According to the present invention, the state of relaxation in a patient may be accurately controlled automatically and overdosing prevented through an electrical stimulus which has no substantial effect Where an advanced state of paralysis is present. When insufficient relaxant is present in the system to have an effective myoneural blocking action, the electric stimulus applied at a selected motor point according to the present invention will produce a muscular contraction at the point of application which through suitable mechanism applied to a finger or foot of the patient, for example, can be made to release additional relaxant solution as needed to accomplish a uniform state of relaxation.

The invention will be described with respect to succinylcholine chloride commercially sold under the name Anectine by the Burroughs Wellcome & Co. (U.S.A.) Inc. lt is capable of functioning with any muscle relaxant preparations.

Accordingly, the invention comprises a method and apparatus yfor administering muscle relaxant drugs which `comprises the steps of periodically applying a low amperage electrical stimulus to a muscle motor point of the patient in applying the contractive force of the stimulus when unhindered by a myoneural block to control the admission of additional relaxant into the patient.

In its simplest form, dosage is given intravenously by the customary gravity flow system although other pumping or pressure flow systems could likewise be used.

The drawings illustrate the application ofthe invention diagrammatically.

traction thereby closing the switch tothe solenoid valve and releasing additional solution. Preferably, this current is given at 10 second intervals although it will be appreciated that other suitable intervals could likewise be employed.

In the drawings, it will be seen that'a' container for succinylcholine solution 10 is connected to a needle 11 inserted into the arm of a patient 12 through the medium of a rubber or plastic tubing 13 between the container andthe needle. The tube 13 is normally closed by means of a'clamp valve 14 at the end of a solenoid 15 normally held in closed position by means of a spring 15a. The functioning of the solenoid 15 is controlled by relay 16 which is connected to a source of electric `current at 17 andto a switch diagrammatically shown at 18.

The switch 18 is shown as being adapted to close on flexion of the finger on the hand of the patient 12. Cloy sure of the switch 18 completes a circuit through relay 16.

Connected with the arm of the patient is an electrode 20 having a contact 20a at the muscular motor point and a second indifferent electrode 21 connected with the patients hand. The two electrodes close a circuit through a motor point stimulator 22 connected to a suitable source of electric power at 23. The motor point stimulator is adapted to deliver a low amperage electrical stimulus to the 'motor point of the patients arm. This electrical stimulus is only effective to produce a contraction when the amount of active relaxant drug in the system has become dissipated to an extent at'which the desired degree of paralysis is no longer obtained. The contraction of the finger closes the switch 18 which in turn operates the relay 16 energizing solenoid 15 which in turn opens the valve 14, releasing an additional supply of muscle relaxant to ilow into the patient.

It will be appreciated that the amount of current ilow#v ing from the motor point stimulator electrode 20 and the electrode 21 Will depend largely uponV the skin resistance of the particular patient. In general, a stepdown transformer delivering 25 volts through a 7,000 ohm resistance will deliver a current in the order ofl one or two milliamperes. This current is adequate'to stimulate the nerve centerscontrolling muscle contraction if the amount of muscle relaxant in the system is not sutiicient to block the muscle response. l

Referring to Fig. 3, a kymograph recording is shown illustrating the degree of contraction obtained in response to ,electrical stimulus according tothe present invention in an animal over a four hour period. In this case, low amperage stimulus was delivered to a patient at. l0 second intervals@ `In the graph, each 11p-stroke of the stylus represents the muscle contraction response at a l0 second interval. The extent of the vertical up-stroke is a measure of the `force o-f the muscle contraction obtained at the particular interval. 'In each instance, the force of this muscle contraction is directly controlled and reduced bythe in- I troduction into the patient of muscle relaxant solution through the valve mechanism above described.

It will be observed that during the initial 30 minute period when no relaxant was administered, very strong muscle contraction was obtained in response to each of the applied electrical stimuli. At the'end of the 30 minute interval, introduction of muscle relaxant was initiated and it will be observed from that point on to the 270 minute interval that a consistent and sustained' degree of muscle'rclaxation was obtained in the patient. During the period of administration, muscle relaxant solution was only introduced through the patient by operation of the solenoid valve in response to muscle contraction at'Y the high points ofthe scroll. At least partial paralysis of the patient was achieved during'theV period when muscle relaxant solution was administered according to the teachings of theV present invention. At the end of the 270 minute period', administration was discontinued and the immediately following long strokes of the stylus indicate the recovery period;

The electrical stimulusY isv preferably applied intermittently at regular intervals to avoid muscle fatigue although under certain conditions, the continuous application of low amperage current during controlled introduction of relaxant may be feasible or even desirable. The electrical means for iow control can be replaced by alternative mechanical or electrical contrivances suitably disposed to control the introduction ofv muscle relaxant in response to a predetermined muscle contraction and such devices are to be deemed equivalents for purposes of this invention.

What is claimedis:

1. A method for the intravenousk administration ,of muscle relaxant drugs comprising the steps of periodically applying a low amperage electrical stimulus to a muscle motorV point controlling a movable body element of the patient' and employing the contractive force of the muscle due to the stimuluswhen unimpaired by myoneural block to control the admission of additional relaxant drug into the patient through movement of said body element.

2. A method `for the intravenous Vadministration of muscle relaxant drugs comprising periodically applying a low amperage electrical current to a muscle motor point of the patient to produce a muscle stimulus to a movable body clement and administering additional muscle relaxant drug in proportion to the muscle contraction. due to said stimulus and movement of the body element.

i 3. The method set forth in accordance with claimY 2 lwherein the stimulus is applied to a muscle motor point controlling a ringer and the resulting contraction used to open a valve controlling the intravenous administrationr of the muscle relaxant.

4. The method set forth in accordance with claim 2 wherein the stimulus is applied to a muscle motor point controlling Ia toe and the resulting contraction used to openl a valve controlling the intravenous administration of the muscle relaxant.

s 'i emanan 5. A method for the parenteral administration of muscle relaxant drugs, which comprises administering a muscle relaxant drug to produce a condition of myoneural block in the subject, applying a low amperage electrical stimulus to the motor point of a muscle controlling an element of the body normally' movable by said muscle, and employing the contractive force of the muscle and resulting movement of the body element when unimpaired by myoneural block to control the admission of additional muscle relaxant drug into the patient. A

6. A method for the parenteral administration of muscle relaxant drugs 'set forth in claim 5, wherein the low amperage electrical stimulus'is periodically applied to the muscle motor point. Y

7. A method for the parenteral administration of muscle relaxant drugs set forth in claim 5, wherein the movement of the body element is employed to actuate a switch to a relay which is connected with a solenoid valve whereby additional muscle relaxant is admitted to the patient on movement of the body element.

8. A method for the parenteral administration of muscle relaxant drugs, which comprises administering a muscle relaxant drug to produce a condition of myoneural block in the subject, applying a low amperage electrical stimulus to the motor point of a muscle controlling a iinger normally movable by said muscle, and employing the contractive force of the muscle and resulting movement of the finger when Vunimpaired by myoneural block torcontrol the admission of additional muscle relaxant drug into the patient.

9. A method` for the parenteral administration of muscle relaxant drugs, which comprises administering a muscle relaxant drug, to produce a condition of myoneural block' in the subject, applying a low amperage electrical stimulus to the motor point of a muscle controlling a toe normally movable by said muscle, and employing the contractive force of the muscle and resulting movement of the toe -when unimpaired by myoneural block to control the admission of additional muscle relaxant drug into the patient.

References Cited in the tile of this patent UNITED STATES PATENTS OTHER REFERENCES Bennett: Electro-diagnosis, published by Lewis (London), 1882, pages 41-42 and 45-47 relied on. l284ll (available in Scientific Library). 

